Systems, assemblies, and methods for treating a bronchial tree

ABSTRACT

Systems, assemblies, and methods to treat pulmonary diseases are used to decrease nervous system input to distal regions of the bronchial tree within the lungs. Treatment systems damage nerve tissue to temporarily or permanently decrease nervous system input. The treatment systems are capable of heating nerve tissue, cooling the nerve tissue, delivering a flowable substance that cause trauma to the nerve tissue, puncturing the nerve tissue, tearing the nerve tissue, cutting the nerve tissue, applying pressure to the nerve tissue, applying ultrasound to the nerve tissue, applying ionizing radiation to the nerve tissue, disrupting cell membranes of nerve tissue with electrical energy, or delivering long acting nerve blocking chemicals to the nerve tissue.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 13/592,075 filed Aug. 22, 2012, now U.S. Pat. No. 9,668,809 issued Jun. 6, 2017, which is a continuation of U.S. patent application Ser. No. 13/452,664 filed Apr. 20, 2012, now U.S. Pat. No. 8,808,280 issued Aug. 19, 2014, which is a continuation of U.S. patent application Ser. No. 13/245,522 filed Sep. 26, 2011, now U.S. Pat. No. 8,226,638 issued Jul. 24, 2012, which is a continuation of U.S. patent application Ser. No. 12/463,304, filed May 8, 2009, now U.S. Pat. No. 8,088,127 issued Jan. 3, 2012, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 61/052,082 filed May 9, 2008; U.S. Provisional Patent Application No. 61/106,490 filed Oct. 17, 2008; and U.S. Provisional Patent Application No. 61/155,449 filed Feb. 25, 2009. Each of these applications is incorporated herein by reference in its entirety.

BACKGROUND Technical Field

The present invention generally relates to systems, assemblies, and methods for treating a bronchial tree, and more particularly, the invention relates to systems, assemblies, and methods for eliciting a desired response.

Description of the Related Art

Pulmonary diseases may cause a wide range of problems that adversely affect performance of the lungs. Pulmonary diseases, such as asthma and chronic obstructive pulmonary disease (“COPD”), may lead to increased airflow resistance in the lungs. Mortality, health-related costs, and the size of the population having adverse effects due to pulmonary diseases are all substantial. These diseases often adversely affect quality of life. Symptoms are varied but often include cough; breathlessness; and wheeze. In COPD, for example, breathlessness may be noticed when performing somewhat strenuous activities, such as running, jogging, brisk walking, etc. As the disease progresses, breathlessness may be noticed when performing non-strenuous activities, such as walking. Over time, symptoms of COPD may occur with less and less effort until they are present all of the time, thereby severely limiting a person's ability to accomplish normal tasks.

Pulmonary diseases are often characterized by airway obstruction associated with blockage of an airway lumen, thickening of an airway wall, alteration of structures within or around the airway wall, or combinations thereof. Airway obstruction can significantly decrease the amount of gas exchanged in the lungs resulting in breathlessness. Blockage of an airway lumen can be caused by excessive intraluminal mucus or edema fluid, or both. Thickening of the airway wall may be attributable to excessive contraction of the airway smooth muscle, airway smooth muscle hypertrophy, mucous glands hypertrophy, inflammation, edema, or combinations thereof. Alteration of structures around the airway, such as destruction of the lung tissue itself, can lead to a loss of radial traction on the airway wall and subsequent narrowing of the airway.

Asthma can be characterized by contraction of airway smooth muscle, smooth muscle hypertrophy, excessive mucus production, mucous gland hypertrophy, and/or inflammation and swelling of airways. These abnormalities are the result of a complex interplay of local inflammatory cytokines (chemicals released locally by immune cells located in or near the airway wall), inhaled irritants (e.g., cold air, smoke, allergens, or other chemicals), systemic hormones (chemicals in the blood such as the anti-inflammatory cortisol and the stimulant epinephrine), local nervous system input (nerve cells contained completely within the airway wall that can produce local reflex stimulation of smooth muscle cells and mucous glands), and the central nervous system input (nervous system signals from the brain to smooth muscle cells and mucous glands carried through the vagus nerve). These conditions often cause widespread temporary tissue alterations and initially reversible airflow obstruction that may ultimately lead to permanent tissue alteration and permanent airflow obstruction that make it difficult for the asthma sufferer to breathe. Asthma can further include acute episodes or attacks of additional airway narrowing via contraction of hyper-responsive airway smooth muscle that significantly increases airflow resistance. Asthma symptoms include recurrent episodes of breathlessness (e.g., shortness of breath or dyspnea), wheezing, chest tightness, and cough.

Emphysema is a type of COPD often characterized by the alteration of lung tissue surrounding or adjacent to the airways in the lungs. Emphysema can involve destruction of lung tissue (e.g., alveoli tissue such as the alveolar sacs) that leads to reduced gas exchange and reduced radial traction applied to the airway wall by the surrounding lung tissue. The destruction of alveoli tissue leaves areas of emphysematous lung with overly large airspaces that are devoid of alveolar walls and alveolar capillaries and are thereby ineffective at gas exchange. Air becomes “trapped” in these larger airspaces. This “trapped” air may cause over-inflation of the lung, and in the confines of the chest restricts the in-flow of oxygen rich air and the proper function of healthier tissue. This results in significant breathlessness and may lead to low oxygen levels and high carbon dioxide levels in the blood. This type of lung tissue destruction occurs as part of the normal aging process, even in healthy individuals. Unfortunately, exposure to chemicals or other substances (e.g., tobacco smoke) may significantly accelerate the rate of tissue damage or destruction. Breathlessness may be further increased by airway obstruction. The reduction of radial traction may cause the airway walls to become “floppy” such that the airway walls partially or fully collapse during exhalation. An individual with emphysema may be unable deliver air out of their lungs due to this airway collapse and airway obstructions during exhalation.

Chronic bronchitis is a type of COPD that can be characterized by contraction of the airway smooth muscle, smooth muscle hypertrophy, excessive mucus production, mucous gland hypertrophy, and inflammation of airway walls. Like asthma, these abnormalities are the result of a complex interplay of local inflammatory cytokines, inhaled irritants, systemic hormones, local nervous system, and the central nervous system. Unlike asthma where respiratory obstruction may be largely reversible, the airway obstruction in chronic bronchitis is primarily chronic and permanent. It is often difficult for a chronic bronchitis sufferer to breathe because of chronic symptoms of shortness of breath, wheezing, and chest tightness, as well as a mucus producing cough.

Different techniques can be used to assess the severity and progression of pulmonary diseases. For example, pulmonary function tests, exercise capacity, and quality of life questionnaires are often used to evaluate subjects. Pulmonary function tests involve objective and reproducible measures of basic physiologic lung parameters, such as total airflow, lung volume, and gas exchange. Indices of pulmonary function tests used for the assessment of obstructive pulmonary diseases include the forced expiratory volume in 1 second (FEV1), the forced vital capacity (FVC), the ratio of the FEV1 to FVC, the total lung capacity (TLC), airway resistance and the testing of arterial blood gases. The FEV1 is the volume of air a patient can exhale during the first second of a forceful exhalation which starts with the lungs completely filled with air. The FEV1 is also the average flow that occurs during the first second of a forceful exhalation. This parameter may be used to evaluate and determine the presence and impact of any airway obstruction. The FVC is the total volume of air a patient can exhale during a forceful exhalation that starts with the lungs completely filled with air. The FEV1/FVC is the fraction of all the air that can be exhaled during a forceful exhalation during the first second. An FEV1/FVC ratio less than 0.7 after the administration of at least one bronchodilator defines the presence of COPD. The TLC is the total amount of air within the lungs when the lungs are completely filled and may increase when air becomes trapped within the lungs of patients with obstructive lung disease. Airway resistance is defined as the pressure gradient between the alveoli and the mouth to the rate of air flow between the alveoli and the mouth. Similarly, resistance of a given airway would be defined as the ratio of the pressure gradient across the given airway to the flow through the airway. Arterial blood gases tests measure the amount of oxygen and the amount of carbon dioxide in the blood and are the most direct method for assessing the ability of the lungs and respiratory system to bring oxygen from the air into the blood and to get carbon dioxide from the blood out of the body.

Exercise capacity tests are objective and reproducible measures of a patient's ability to perform activities. A six minute walk test (6MWT) is an exercise capacity test in which a patient walks as far as possible over a flat surface in 6 minutes. Another exercise capacity test involves measuring the maximum exercise capacity of a patient. For example, a physician can measure the amount of power the patient can produce while on a cycle ergometer. The patient can breathe 30 percent oxygen and the work load can increase by 5-10 watts every 3 minutes.

Quality of life questionnaires assess a patient's overall health and well being. The St. George's Respiratory Questionnaire is a quality of life questionnaire that includes 75 questions designed to measure the impact of obstructive lung disease on overall health, daily life, and perceived well-being. The efficacy of a treatment for pulmonary diseases can be evaluated using pulmonary function tests, exercise capacity tests, and/or questionnaires. A treatment program can be modified based on the results from these tests and/or questionnaires.

Treatments, such as bronchial thermoplasty, involve destroying smooth muscle tone by ablating the airway wall in a multitude of bronchial branches within the lung thereby eliminating both smooth muscles and nerves in the airway walls of the lung. The treated airways are unable to respond favorably to inhaled irritants, systemic hormones, and both local and central nervous system input. Unfortunately, this destruction of smooth muscle tone and nerves in the airway wall may therefore adversely affect lung performance. For example, inhaled irritants, such as smoke or other noxious substances, normally stimulate lung irritant receptors to produce coughing and contracting of airway smooth muscle. Elimination of nerves in the airway walls removes both local nerve function and central nervous input, thereby eliminating the lung's ability to expel noxious substances with a forceful cough. Elimination of airway smooth muscle tone may eliminate the airways' ability to constrict, thereby allowing deeper penetration of unwanted substances, such as noxious substances, into the lung.

Additionally, methods of destroying smooth muscle tone by ablating portions of the airway wall, such as bronchial thermoplasty, often have the following limitations: 1) inability to affect airways that are not directly ablated, typically airways smaller than approximately 3.0 mm which may also be narrowed in obstructive lung diseases such as asthma, emphysema, and chronic bronchitis; 2) short-term swelling that causes acute respiratory problems due to perioperative swelling in airways already narrowed by obstructive lung disease effects; 3) hundreds of applications to airways within the lungs may be required to alter overall lung functionality; 4) since multiple generations of airways within the lung are treated (typically generations 2-8), targeting lung airways without missing or over treating specific lung airway sections can be problematic; and, 5) separating the treating step into stages may be required to reduce the healing load on the lung which adds additional risk and cost with each additional bronchoscopy treatment session.

Both asthma and COPD are serious diseases with growing numbers of sufferers. Current management techniques, which include prescription drugs, are neither completely successful nor free from side effects. Additionally, many patients do not comply with their drug prescription dosage regiment. Accordingly, it would be desirable to provide a treatment which improves resistance to airflow without the need for patient compliance.

BRIEF SUMMARY

In some embodiments, a treatment system can be navigated through airways, such as the right and left main bronchi of the lung root as well as more distal airways within the lungs, to treat a wide range of pulmonary symptoms, conditions, and/or diseases, including, without limitation, asthma, COPD, obstructive lung diseases, or other diseases that lead to an increased resistance to airflow in the lungs. The treatment system can treat one or more target sites without treating non-targeted sites. Even if targeted anatomical features (e.g., nerves, glands, membranes, and the like) of main bronchi, lobar bronchi, segmental bronchi or subsegmental bronchi are treated, non-targeted anatomical features can be substantially unaltered. For example, the treatment system can destroy nerve tissue at target sites without destroying to any significant extent non-targeted tissue that can remain functional after performing treatment.

At least some embodiments disclosed herein can be used to affect nerve tissue of nerve trunks outside of airway walls while maintaining the airways ability to move (e.g., constrict and/or expand) in response to, for example, inhaled irritants, local nerve stimulation, systemic hormones, or combinations thereof. In some embodiments, the nerve tissue of nerve trunks is destroyed without eliminating smooth muscle tone. After damaging the nerve trunks, the airways have at least some muscle tone such that the smooth muscles in the airways, if stimulated, can alter the diameter of the airway to help maintain proper lung function. A wide range of different physiological functions associated with smooth muscle tone can be maintained before, during, and/or after the treatment.

In some embodiments, a method for treating one or more pulmonary diseases is provided. The method includes damaging nerve tissue of a vagal nerve trunk extending along the outside of a bronchial tree airway so as to attenuate nervous system signals transmitted to a portion of the bronchial tree. The nerve trunk may be the main stem of a nerve, comprising a bundle of nerve fibers bound together by a tough sheath of connective tissue. In some embodiments, the nerve tissue is damaged while maintaining a functionality of one or more anatomical features, such as blood vessels, also extending alongside the airway so as to preserve a respiratory function of the portion of the bronchial tree after the nerve tissue is damaged.

Conditions and symptoms associated with pulmonary diseases can be reduced, limited, or substantially eliminated. For example, airway obstruction can be treated to elicit reduced airflow resistance. Blood vessels or other tissue can remain intact and functional during and/or after treatment. The respiratory function that is preserved can include gas exchange, mucociliary transport, and the like. In some embodiments, the nerve tissue, such as nerve tissue of nerve trunks located outside of the airway, is damaged without damaging to any significant extent a portion of the airway wall that is circumferentially adjacent to the damaged nerve tissue. Accordingly, non-targeted tissue can be substantially unaltered by the damage to the airway nerve tissue.

Damaging the nerve tissue can involve delivering energy to the nerve tissue such that the destroyed nerve tissue impedes or stops the transmission of nervous system signals to nerves more distal along the bronchial tree. The nerve tissue can be temporarily or permanently damaged by delivering different types of energy to the nerve tissue. For example, the nerve tissue can be thermally damaged by increasing a temperature of the nerve tissue to a first temperature (e.g., an ablation temperature) while the wall of the airway is at a second temperature that is less than the first temperature. In some embodiments, a portion of the airway wall positioned radially inward from the nerve tissue can be at the first temperature so as to prevent permanent damage to the portion of the airway wall. The first temperature can be sufficiently high to cause permanent destruction of the nerve tissue. In some embodiments, the nerve tissue is part of a nerve trunk located in connective tissue outside of the airway wall. The smooth muscle and nerve tissue in the airway wall can remain functional to maintain a desired level of smooth muscle tone. The airway can constrict/dilate in response to stimulation (e.g., stimulation caused by inhaled irritants, the local nervous system, or systemic hormones). In other embodiments, the nerve tissue is part of a nerve branch or nerve fibers in the airway wall. In yet other embodiments, both nerve tissue of the nerve trunk and nerve tissue of nerve branches/fibers are simultaneously or sequentially damaged. Various types of activatable elements, such as ablation elements, can be utilized to output the energy.

In some embodiments, a method for treating a subject comprises moving an elongate assembly along a lumen of an airway of a bronchial tree. The airway includes a first tubular section, a second tubular section, a treatment site between the first tubular section and the second tubular section, and a nerve extending along at least the first tubular section, the treatment site, and the second tubular section. The nerve can be within or outside of the airway wall. In some embodiments, the nerve is a nerve trunk outside of the airway wall and connected to a vagus nerve.

The method can further include damaging a portion of the nerve at the treatment site to substantially prevent signals from traveling between the first tubular section and the second tubular section via the nerve. In some embodiments, blood flow between the first tubular section and the second tubular section can be maintained while damaging a portion of the nerve. The continuous blood flow can maintain desired functioning of distal lung tissue.

The second tubular section of the airway may dilate in response to the damage to the nerve. Because nervous system signals are not delivered to smooth muscle of the airway of the second tubular section, smooth muscle can relax so as to cause dilation of the airway, thereby reducing airflow resistance, even airflow resistance associated with pulmonary diseases. In some embodiments, nerve tissue can be damaged to cause dilation of substantially all the airways distal to the damaged tissue. The nerve can be a nerve trunk, nerve branch, nerve fibers, and/or other accessible nerves.

The method, in some embodiments, includes detecting one or one attributes of an airway and evaluating whether the nerve tissue is damaged based on the attributes. Evaluating includes comparing measured attributes of the airway (e.g., comparing measurements taken at different times), comparing measured attributes and stored values (e.g., reference values), calculating values based on measured attributes, monitoring changes of attributes, combinations thereof, or the like.

In some embodiments, a method for treating a subject includes moving an intraluminal device along a lumen of an airway of a bronchial tree. A portion of the airway is denervated using the intraluminal device. In some embodiments, the portion of the airway is denervated without irreversibly damaging to any significant extent an inner surface of the airway. In some embodiments, a portion of a bronchial tree is denervated without irreversibly damaging to any significant extent nerve tissue (e.g., nerve tissue of nerve fibers) within the airway walls of the bronchial tree. The inner surface can define the lumen along which the intraluminal device was moved.

The denervating process can be performed without destroying at least one artery extending along the airway. In some embodiments, substantially all of the arteries extending along the airway are preserved during the denervating process. In some embodiments, one or more nerves embedded in the wall of the airway can be generally undamaged during the denervating process. The destroyed nerves can be nerve trunks outside of the airway.

In some embodiments, the denervating process can decrease smooth muscle tone of the airway to achieve a desired increased airflow into and out of the lung. In some embodiments, the denerving process causes a sufficient decrease of smooth muscle tone so as to substantially increase airflow into and out of the lung. For example, the subject may have an increase in FEV1 of at least 10% over a baseline FEV1. As such, the subject may experience significant improved lung function when performing normal everyday activities, even strenuous activities. In some embodiments, the decrease of airway smooth muscle tone is sufficient to cause an increase of FEV1 in the range of about 10% to about 30%. Any number of treatment sites can be treated either in the main bronchi, segmental bronchi or subsegmental bronchi to achieve the desired increase in lung function.

In some embodiments, an elongate assembly for treating a lung is adapted to damage nerve tissue of a nerve trunk so as to attenuate nervous system signals transmitted to a more distal portion of the bronchial tree. The tissue can be damaged while the elongated assembly extends along a lumen of the bronchial tree. A delivery assembly can be used to provide access to the nerve tissue.

In some other embodiments, a system for treating a subject includes an elongate assembly dimensioned to move along a lumen of an airway of a bronchial tree. The elongate assembly is adapted to attenuate signals transmitted by nerve tissue, such as nerve tissue of nerve trunks, while not irreversibly damaging to any significant extent an inner surface of the airway. The elongate assembly can include an embeddable distal tip having at least one actuatable element, such as an ablation element. The ablation element can ablate various types of nerve tissue when activated. In some embodiments, the ablation element includes one or more electrodes operable to output radiofrequency energy.

In some embodiments, a method comprises damaging nerve tissue of a first main bronchus to substantially prevent nervous system signals from traveling to substantially all distal bronchial branches connected to the first main bronchus. In some embodiments, most or all of the bronchial branches distal to the first main bronchus are treated. The nerve tissue, in certain embodiments, is positioned between a trachea and a lung through which the bronchial branches extend. The method further includes damaging nerve tissue of a second main bronchus to substantially prevent nervous system signals from traveling to substantially all distal bronchial branches connected to the second main bronchus. A catheter assembly can be used to damage the nerve tissue of the first main bronchus and to damage the nerve tissue of the second main bronchus without removing the catheter assembly from a trachea connected to the first and second bronchi.

In some embodiments, a method comprises denervating most of a portion of a bronchial tree to substantially prevent nervous system signals from traveling to substantially all bronchial branches of the portion. In certain embodiments, denervating procedures involve damaging nerve tissue using less than about 100 applications of energy, 50 applications of energy, 36 applications of energy, 18 applications of energy, 10 applications of energy, or 3 applications of energy. Each application of energy can be at a different treatment site. In some embodiments, substantially all bronchial branches in one or both lungs are denervated by the application of energy.

In certain embodiments, one or more detection elements are used to detect attributes of airways before, during, and/or after therapy. A detection element can physically contact an inner surface of the airway to evaluate physical properties of the airway. The detection element may include one or more inflatable balloons that can be positioned distal to targeted tissue.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the Figures, identical reference numbers identify similar elements or acts.

FIG. 1 is an illustration of lungs, blood vessels, and nerves near to and in the lungs.

FIG. 2A is a schematic view of a treatment system positioned within a left main bronchus according to one embodiment.

FIG. 2B is a schematic view of a treatment system and an instrument extending distally from the treatment system.

FIG. 3 is a cross-sectional view of an airway of a bronchial tree surrounding a distal tip of a treatment system positioned along an airway lumen according to one embodiment.

FIG. 4 is a cross-sectional view of an airway of a bronchial tree surrounding a distal tip of a treatment system when smooth muscle of the airway is constricted and mucus is in an airway lumen according to one embodiment.

FIG. 5A is a partial cross-sectional view of a treatment system having a delivery assembly and an elongate assembly extending through and out of the delivery assembly.

FIG. 5B is an illustration of a distal tip of the elongate assembly of FIG. 5A positioned to affect nerve tissue of a nerve trunk.

FIG. 6 is a side elevational view of a delivery assembly in a lumen of a bronchial airway according to one embodiment.

FIG. 7 is a side elevational view of a distal tip of an elongate assembly moving through the delivery assembly of FIG. 6.

FIG. 8 is a side elevational view of the distal tip of the elongate assembly protruding from the delivery assembly according to one embodiment.

FIG. 9 is an enlarged partial cross-sectional view of the distal tip of FIG. 8, wherein the distal tip extends into a wall of the airway.

FIG. 10A is a side elevational view of a self-expanding ablation assembly in an airway according to one embodiment.

FIG. 10B is a front view of the ablation assembly of FIG. 10A.

FIG. 11A is a side elevational view of another embodiment of a self-expanding ablation assembly in an airway.

FIG. 11B is a front view of the ablation assembly of FIG. 11A.

FIG. 12A is a partial cross-sectional view of a treatment system having a delivery assembly and a separate elongate assembly within the delivery assembly according to one embodiment.

FIG. 12B is a front view of the treatment system of FIG. 12A.

FIG. 13A is a cross-sectional view of a delivery assembly delivering energy to a treatment site according to one embodiment.

FIG. 13B is a front view of the delivery assembly of FIG. 13A.

FIG. 14A is a partial cross-sectional view of a treatment system having an elongate assembly with a port positioned in an airway wall according to one embodiment.

FIG. 14B is a front view of the treatment system of FIG. 14A.

FIG. 15A is a side elevational view of a treatment system having an expandable assembly.

FIG. 15B is a cross-sectional view of the expandable assembly of FIG. 15A.

FIG. 16 is a graph of the depth of tissue versus temperature of the tissue.

FIG. 17 is a side elevational view of the expandable assembly of FIG. 15A in an airway.

FIG. 18 is a cross-sectional view of the expandable assembly of FIG. 15A and an airway surrounding the expandable assembly.

FIG. 19A is a side elevational view of a treatment system having an expandable assembly, in accordance with one embodiment.

FIG. 19B is a cross-sectional view of the expandable assembly of FIG. 19A.

FIG. 20A is a side elevational view of a treatment system having an expandable assembly, in accordance with another embodiment.

FIG. 20B is a cross-sectional view of the expandable assembly of FIG. 20A.

FIG. 21 is a cross-sectional view of the expandable assembly of FIG. 20A and an airway surrounding the expandable assembly.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the invention. However, one skilled in the art will understand that the invention may be practiced without these details. In other instances, well-known structures associated with catheter systems, delivery assemblies, activatable elements, circuitry, and electrodes have not been described in detail to avoid unnecessarily obscuring descriptions of the embodiments of the invention.

Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as “comprises” and “comprising” are to be construed in an open, inclusive sense, that is, as “including but not limited to.”

FIG. 1 illustrates human lungs 10 having a left lung 11 and a right lung 12. A trachea 20 extends downwardly from the nose and mouth and divides into a left main bronchus 21 and a right main bronchus 22. The left main bronchus 21 and right main bronchus 22 each branch to form a lobar, segmental bronchi, and sub-segmental bronchi, which have successively smaller diameters and shorter lengths in the outward direction (i.e., the distal direction). A main pulmonary artery 30 originates at a right ventricle of the heart and passes in front of a lung root 24. At the lung root 24, the artery 30 branches into a left and right pulmonary artery, which in turn branch to form a network of branching blood vessels. These blood vessels can extend alongside airways of a bronchial tree 27. The bronchial tree 27 includes the left main bronchus 21, the right main bronchus 22, bronchioles, and alveoli. Vagus nerves 41, 42 extend alongside the trachea 20 and branch to form nerve trunks 45.

The left and right vagus nerves 41, 42 originate in the brainstem, pass through the neck, and descend through the chest on either side of the trachea 20. The vagus nerves 41, 42 spread out into nerve trunks 45 that include the anterior and posterior pulmonary plexuses that wrap around the trachea 20, the left main bronchus 21, and the right main bronchus 22. The nerve trunks 45 also extend along and outside of the branching airways of the bronchial tree 27. Nerve trunks 45 are the main stem of a nerve, comprising a bundle of nerve fibers bound together by a tough sheath of connective tissue.

The prime function of the lungs 10 is to exchange oxygen from air into the blood and to exchange carbon dioxide from the blood to the air. The process of gas exchange begins when oxygen rich air is pulled into the lungs 10. Contraction of the diaphragm and intercostal chest wall muscles cooperate to decrease the pressure within the chest to cause the oxygen rich air to flow through the airways of the lungs 10. For example, air passes through the mouth and nose, the trachea 20, then through the bronchial tree 27. The air is ultimately delivered to the alveolar air sacs for the gas exchange process.

Oxygen poor blood is pumped from the right side of the heart through the pulmonary artery 30 and is ultimately delivered to alveolar capillaries. This oxygen poor blood is rich in carbon dioxide waste. Thin semi-permeable membranes separate the oxygen poor blood in capillaries from the oxygen rich air in the alveoli. These capillaries wrap around and extend between the alveoli. Oxygen from the air diffuses through the membranes into the blood, and carbon dioxide from the blood diffuses through the membranes to the air in the alveoli. The newly oxygen enriched blood then flows from the alveolar capillaries through the branching blood vessels of the pulmonary venous system to the heart. The heart pumps the oxygen rich blood throughout the body. The oxygen spent air in the lung is exhaled when the diaphragm and intercostal muscles relax and the lungs and chest wall elastically return to the normal relaxed states. In this manner, air can flow through the branching bronchioles, the bronchi 21, 22, and the trachea 20 and is ultimately expelled through the mouth and nose.

A treatment system 198 of FIG. 2A can be used to treat the lungs 10 to adjust air flow during expiration or inhalation, or both. For example, airways can be enlarged (e.g., dilated) to decrease air flow resistance to increase gas exchange. The treatment system 198 can affect nerve tissue, such as nerve tissue of a nerve trunk, to dilate airways.

In some embodiments, the treatment system 198 targets the nervous system which provides communication between the brain and the lungs 10 using electrical and chemical signals. A network of nerve tissue of the autonomic nervous system senses and regulates activity of the respiratory system and the vasculature system. Nerve tissue includes fibers that use chemical and electrical signals to transmit sensory and motor information from one body part to another. For example, the nerve tissue can transmit motor information in the form of nervous system input, such as a signal that causes contraction of muscles or other responses. The fibers can be made up of neurons. The nerve tissue can be surrounded by connective tissue, i.e., epineurium. The autonomic nervous system includes a sympathetic system and a parasympathetic system. The sympathetic nervous system is largely involved in “excitatory” functions during periods of stress. The parasympathetic nervous system is largely involved in “vegetative” functions during periods of energy conservation. The sympathetic and parasympathetic nervous systems are simultaneously active and generally have reciprocal effects on organ systems. While innervation of the blood vessels originates from both systems, innervation of the airways are largely parasympathetic in nature and travel between the lung and the brain in the right vagus nerve 42 and the left vagus nerve 41.

The treatment system 198 can perform any number of procedures on one or more of these nerve trunks 45 to affect the portion of the lung associated with those nerve trunks. Because some of the nerve tissue in the network of nerve trunks 45 coalesce into other nerves (e.g., nerves connected to the esophagus, nerves though the chest and into the abdomen, and the like), the treatment system 198 can treat specific sites to minimize, limit, or substantially eliminate unwanted damage of those other nerves. Some fibers of anterior and posterior pulmonary plexuses coalesce into small nerve trunks which extend along the outer surfaces of the trachea 20 and the branching bronchi and bronchioles as they travel outward into the lungs 10. Along the branching bronchi, these small nerve trunks continually ramify with each other and send fibers into the walls of the airways, as discussed in connection with FIGS. 3 and 4.

The treatment system 198 can affect specific nerve tissue, such as vagus nerve tissue, associated with particular sites of interest. Vagus nerve tissue includes efferent fibers and afferent fibers oriented parallel to one another within a nerve branch. The efferent nerve tissue transmits signals from the brain to airway effector cells, mostly airway smooth muscle cells and mucus producing cells. The afferent nerve tissue transmits signals from airway sensory receptors, which respond variously to irritants and stretch, to the brain. While efferent nerve tissue innervates smooth muscle cells all the way from the trachea 20 to the terminal bronchioles, the afferent fiber innervation is largely limited to the trachea 20 and larger bronchi. There is a constant, baseline tonic activity of the efferent vagus nerve tissues to the airways which causes a baseline level of smooth muscle contraction and mucous secretion.

The treatment system 198 can affect the efferent and/or the afferent tissues to control airway smooth muscle (e.g., innervate smooth muscle) and mucous secretion. The contraction of airway smooth muscle and excess mucous secretion associated with pulmonary diseases often results in relatively high air flow resistance causing reduced gas exchange and decreased lung performance.

For example, the treatment system 198 can attenuate the transmission of signals traveling along the vagus nerves 41, 42 that cause muscle contractions, mucus production, and the like. Attenuation can include, without limitation, hindering, limiting, blocking, and/or interrupting the transmission of signals. For example, the attenuation can include decreasing signal amplitude of nerve signals or weakening the transmission of nerve signals. Decreasing or stopping nervous system input to distal airways can alter airway smooth muscle tone, airway mucus production, airway inflammation, and the like, thereby controlling airflow into and out of the lungs 10. In some embodiments, the nervous system input can be decreased to correspondingly decrease airway smooth muscle tone. In some embodiments, the airway mucus production can be decreased a sufficient amount to cause a substantial decrease in coughing and/or in airflow resistance. Signal attenuation may allow the smooth muscles to relax and prevent, limit, or substantially eliminate mucus production by mucous producing cells. In this manner, healthy and/or diseased airways can be altered to adjust lung function. After treatment, various types of questionnaires or tests can be used to assess the subject's response to the treatment. If needed or desired, additional procedures can be performed to reduce the frequency of coughing, decrease breathlessness, decrease wheezing, and the like.

Main bronchi 21, 22 (i.e., airway generation 1) of FIG. 1 can be treated to affect distal portions of the bronchial tree 27. In some embodiments, the left and right main bronchi 21, 22 are treated at locations along the left and right lung roots 24 and outside of the left and right lungs 11, 12. Treatment sites can be distal to where vagus nerve branches connect to the trachea and the main bronchi 21, 22 and proximal to the lungs 11, 12. A single treatment session involving two therapy applications can be used to treat most of or the entire bronchial tree 27. Substantially all of the bronchial branches extending into the lungs 11, 12 may be affected to provide a high level of therapeutic effectiveness. Because the bronchial arteries in the main bronchi 21, 22 have relatively large diameters and high heat sinking capacities, the bronchial arteries may be protected from unintended damage due to the treatment.

In some embodiments, one of the left and right main bronchi 21, 22 is treated to treat one side of the bronchial tree 27. The other main bronchus 21, 22 can be treated based on the effectiveness of the first treatment. For example, the left main bronchus 21 can be treated to treat the left lung 11. The right main bronchus 22 can be treated to treat the right lung 12. In some embodiments, a single treatment system can damage the nerve tissue of one of the bronchi 21, 22 and can damage the nerve tissue of the other main bronchus 21, 22 without removing the treatment system from the trachea 20. Nerve tissue positioned along the main bronchi 21, 22 can thus be damaged without removing the treatment system from the trachea 20. In some embodiments, a single procedure can be performed to conveniently treat substantially all, or at least a significant portion (e.g., at least 50%, 70%, 80%, 90% of the bronchial airways), of the patient's bronchial tree. In other procedures, the treatment system can be removed from the patient after treating one of the lungs 11, 12. If needed, the other lung 11, 12 can be treated in a subsequent procedure.

The treatment system 198 of FIGS. 2A and 2B can treat airways that are distal to the main bronchi 21, 22. For example, the treatment system 198 can be positioned in higher generation airways (e.g., airway generations >2) to affect remote distal portions of the bronchial tree 27. The treatment system 198 can be navigated through tortuous airways to perform a wide range of different procedures, such as, for example, denervation of a portion of a lobe, an entire lobe, multiple lobes, or one lung or both lungs. In some embodiments, the lobar bronchi are treated to denervate lung lobes. For example, one or more treatment sites along a lobar bronchus may be targeted to denervate an entire lobe connected to that lobar bronchus. Left lobar bronchi can be treated to affect the left superior lobe and/or the left inferior lobe. Right lobar bronchi can be treated to affect the right superior lobe, the right middle lobe, and/or the right inferior lobe. Lobes can be treated concurrently or sequentially. In some embodiments, a physician can treat one lobe. Based on the effectiveness of the treatment, the physician can concurrently or sequentially treat additional lobe(s). In this manner, different isolated regions of the bronchial tree can be treated.

The treatment system 198 can also be used in segmental or subsegmental bronchi. Each segmental bronchus may be treated by delivering energy to a single treatment site along each segmental bronchus. For example, energy can be delivered to each segmental bronchus of the right lung. In some procedures, ten applications of energy can treat most of or substantially all of the right lung. In some procedures, most or substantially all of both lungs are treated using less than thirty-six different applications of energy. Depending on the anatomical structure of the bronchial tree, segmental bronchi can often be denervated using one or two applications of energy.

The treatment system 198 can affect nerve tissue while maintaining function of other tissue or anatomical features, such as the mucous glands, cilia, smooth muscle, body vessels (e.g., blood vessels), and the like. Nerve tissue includes nerve cells, nerve fibers, dendrites, and supporting tissue, such as neuroglia. Nerve cells transmit electrical impulses, and nerve fibers are prolonged axons that conduct the impulses. The electrical impulses are converted to chemical signals to communicate with effector cells or other nerve cells. By way of example, the treatment system 198 is capable of denervating a portion of an airway of the bronchial tree 27 to attenuate one or more nervous system signals transmitted by nerve tissue. Denervating can include damaging all of the nerve tissue of a section of a nerve trunk along an airway to stop substantially all of the signals from traveling through the damaged section of the nerve trunk to more distal locations along the bronchial tree. If a plurality of nerve trunks extends along the airway, each nerve trunk can be damaged. As such, the nerve supply along a section of the bronchial tree can be cut off. When the signals are cut off, the distal airway smooth muscle can relax leading to airway dilation. This airway dilation reduces airflow resistance so as to increase gas exchange in the lungs 10, thereby reducing, limiting, or substantially eliminating one or more symptoms, such as breathlessness, wheezing, chest tightness, and the like. Tissue surrounding or adjacent to the targeted nerve tissue may be affected but not permanently damaged. In some embodiments, for example, the bronchial blood vessels along the treated airway can deliver a similar amount of blood to bronchial wall tissues and the pulmonary blood vessels along the treated airway can deliver a similar amount of blood to the alveolar sacs at the distal regions of the bronchial tree 27 before and after treatment. These blood vessels can continue to transport blood to maintain sufficient gas exchange. In some embodiments, airway smooth muscle is not damaged to a significant extent. For example, a relatively small section of smooth muscle in an airway wall which does not appreciably impact respiratory function may be reversibly altered. If energy is used to destroy the nerve tissue outside of the airways, a therapeutically effective amount of energy does not reach a significant portion of the non-targeted smooth muscle tissue.

The treatment system 198 of FIG. 2A includes a treatment controller 202 and an intraluminal elongate assembly 200 connected to the controller 202. The elongate assembly 200 can be inserted into the trachea 20 and navigated into and through the bronchial tree 27 with or without utilizing a delivery assembly. The elongate assembly 200 includes a distal tip 203 capable of selectively affecting tissue.

The controller 202 of FIG. 2A can include one or more processors, microprocessors, digital signal processors (DSPs), field programmable gate arrays (FPGA), and/or application-specific integrated circuits (ASICs), memory devices, buses, power sources, and the like. For example, the controller 202 can include a processor in communication with one or more memory devices. Buses can link an internal or external power supply to the processor. The memories may take a variety of forms, including, for example, one or more buffers, registers, random access memories (RAMs), and/or read only memories (ROMs). The controller 202 may also include a display, such as a screen.

In some embodiments, the controller 202 has a closed loop system or an open loop system. For example, the controller 202 can have a closed loop system, whereby the power to the distal tip 203 is controlled based upon feedback signals from one or more sensors configured to transmit (or send) one or more signals indicative of one or more tissue characteristics, energy distribution, tissue temperature, or any other measurable parameters of interest. Based on those readings, the controller 202 can then adjust operation of the distal tip 203. Alternatively, the treatment system 198 can be an open loop system wherein the operation of the distal tip 203 is set by user input. For example, the treatment system 198 may be set to a fixed power mode. It is contemplated that the treatment system 198 can be repeatedly switched between a closed loop system and an open loop system to treat different types of sites.

The distal tip 203 of FIGS. 2A-4 can target various sites in the lungs 10, including, without limitation, nerve tissue (e.g., tissue of the vagus nerves 41, 42, nerve trunks 45, etc.), fibrous tissue, diseased or abnormal tissues (e.g., cancerous tissue, inflamed tissue, and the like), muscle tissue, blood, blood vessels, anatomical features (e.g., membranes, glands, cilia, and the like), or other sites of interest. Various types of distal tips are discussed in connection with FIGS. 5A-14B.

FIG. 3 is a transverse cross-sectional view of a healthy airway 100, illustrated as a bronchial tube. The distal tip 203 is positioned along a lumen 101 defined by an inner surface 102 of the airway 100. The illustrated inner surface 102 is defined by a folded layer of epithelium 110 surrounded by stroma 112 a. A layer of smooth muscle tissue 114 surrounds the stroma 112 a. A layer of stroma 112 b is between the muscle tissue 114 and connective tissue 124. Mucous glands 116, cartilage plates 118, blood vessels 120, and nerve fibers 122 are within the stroma layer 112 b. Bronchial artery branches 130 and nerve trunks 45 are exterior to a wall 103 of the airway 100. The illustrated arteries 130 and nerve trunks 45 are within the connective tissue 124 surrounding the airway wall 103 and can be oriented generally parallel to the airway 100. In FIG. 1, for example, the nerve trunks 45 originate from the vagus nerves 41, 42 and extend along the airway 100 towards the air sacs. The nerve fibers 122 are in the airway wall 103 and extend from the nerve trunks 45 to the muscle tissue 114. Nervous system signals are transmitted from the nerve trunks 45 to the muscle 114 via the nerve fibers 122.

The distal tip 203 of FIG. 3 can damage, excite, or otherwise elicit a desired response of the cilia along the epithelium 110 in order to control (e.g., increase or decrease) mucociliary transport. Many particles are inhaled as a person breathes, and the airways function as a filter to remove the particles from the air. The mucociliary transport system functions as a self-cleaning mechanism for all the airways throughout the lungs 10. The mucociliary transport is a primary method for mucus clearance from distal portions of the lungs 10, thereby serving as a primary immune barrier for the lungs 10. For example, the inner surface 102 of FIG. 3 can be covered with cilia and coated with mucus. As part of the mucociliary transport system, the mucus entraps many inhaled particles (e.g., unwanted contaminates such as tobacco smoke) and moves these particles towards the larynx. The ciliary beat of cilia moves a continuous carpet of mucus and entrapped particles from the distal portions of the lungs 10 past the larynx and to the pharynx for expulsion from the respiratory system. The distal tip 203 can damage the cilia to decrease mucociliary transport or excite the cilia to increase mucociliary transport.

In some embodiments, the distal tip 203 selectively treats targeted treatment sites inside of the airway wall 103 (e.g., anatomical features in the stromas 112 a, 112 b). For example, the mucous glands 116 can be damaged to reduce mucus production a sufficient amount to prevent the accumulation of mucus that causes increased air flow resistance while preserving enough mucus production to maintain effective mucociliary transport, if needed or desired. In some embodiments, for example, the distal tip 203 outputs ablative energy that travels through the inner periphery of the airway wall 103 to the mucous glands 116. In other embodiments, the distal tip 203 is inserted into the airway wall 103 to position the distal tip 203 next to the mucous glands 116. The embedded distal tip 203 then treats the mucous glands 116 while limiting treatment of surrounding tissue. The distal tip 203 can also be used to destroy nerve branches/fibers passing through the airway wall 103 or other anatomical features in the airway wall 103.

If the airway 100 is overly constricted, the air flow resistance of the airway 100 may be relatively high. The distal tip 203 can relax the muscle tissue 114 to dilate the airway 100 to reduce air flow resistance, thereby allowing more air to reach the alveolar sacs for the gas exchange process. Various airways of the bronchial tree 47 may have muscles that are constricted in response to signals traveling through the nerve trunks 45. The tip 203 can damage sites throughout the lungs 10 to dilate constricted airways.

FIG. 4 is a transverse cross-sectional view of a portion of the airway 100 that has smooth muscle tissue 114 in a contracted state and mucus 150 from hypertrophied mucous glands 116. The contracted muscle tissue 114 and mucus 150 cooperate to partially obstruct the lumen 101. The distal tip 203 can relax the smooth muscle tissue 114 and reduce, limit, or substantially eliminate mucus production of the mucous glands 116. The airway 100 may then dilate and the amount of mucus 150 may be reduced, to effectively enlarge the lumen 101.

The distal tip 203 of FIGS. 3 and 4 can deliver different types of energy. As used herein, the term “energy” is broadly construed to include, without limitation, thermal energy, cryogenic energy (e.g., cooling energy), electrical energy, acoustic energy (e.g., ultrasonic energy), radio frequency energy, pulsed high voltage energy, mechanical energy, ionizing radiation, optical energy (e.g., light energy), and combinations thereof, as well as other types of energy suitable for treating tissue. By way of example, thermal energy can be used to heat tissue. Mechanical energy can be used to puncture, tear, cut, crush, or otherwise physically damage tissue. In some embodiments, the distal tip 203 applies pressure to tissue in order to temporarily or permanently damage tissue. Electrical energy is particularly well suited for damaging cell membranes, such as the cell membranes of nerve trunk tissue or other targeted anatomical features. Acoustic energy can be emitted as continuous or pulsed waves, depending on the parameters of a particular application. Additionally, acoustic energy can be emitted in waveforms having various shapes, such as sinusoidal waves, triangle waves, square waves, or other wave forms.

In some embodiments, a fluid (e.g., a liquid, gas, or mixtures thereof) is employed to damage tissue. The distal tip 203 can include one or more flow elements through which the fluid can circulate to control the surface temperature of the flow element. The flow element can be one or more balloons, expandable members, and the like. The fluid can be heated/cooled saline, cryogenic fluids, and the like. Additionally or alternatively, the distal tip 203 can include one or more ports through which fluid flows to traumatize tissue.

In some embodiments, the distal tip 203 delivers one or more substances (e.g., radioactive seeds, radioactive materials, etc.), treatment agents, and the like. Exemplary non-limiting treatment agents include, without limitation, one or more antibiotics, anti-inflammatory agents, pharmaceutically active substances, bronchoconstrictors, bronchodilators (e.g., beta-adrenergic agonists, anticholinergics, etc.), nerve blocking drugs, photoreactive agents, or combinations thereof. For example, long acting or short acting nerve blocking drugs (e.g., anticholinergics) can be delivered to the nerve tissue to temporarily or permanently attenuate signal transmission. Substances can also be delivered directly to the nerves 122 or the nerve trunks 45, or both, to chemically damage the nerve tissue.

FIGS. 5A-14B illustrate embodiments for delivery along a lumen of an airway. The illustrated embodiments are just some examples of the types of treatment systems capable of performing particular procedures. It should be recognized that each of the treatment systems described herein can be modified to treat tissue at different locations, depending on the treatment to be performed. Treatment can be performed in airways that are either inside or outside of the left and right lungs. FIGS. 5A-13B illustrate treatment systems capable of outputting energy. These treatment systems may continuously output energy for a predetermined period of time while remaining stationary. Alternatively, the treatment systems may be pulsed, may be activated multiple times, or may be actuated in a combination of any of these ways. Different energy application patterns can be achieved by configuring the treatment system itself or may involve moving the treatment assembly or any of its components to different locations.

Referring to FIG. 5A, a treatment system 198A includes an elongate assembly 200A that has a distal tip 203A positioned along the airway 100. The elongate assembly 200A extends through a working lumen 401 of a delivery assembly 400 and includes a flexible shaft 500 and a deployable ablation assembly 520 protruding from the shaft 500.

The shaft 500 can be a generally straight shaft that is bent as it moves along the lumen 401. In some embodiments, the shaft 500 has a preformed non-linear section 503 to direct the ablation assembly 520 towards the airway wall 103. As shown in FIG. 5A, the lumen 401 can have a diameter that is significantly larger than the outer diameter of the shaft 500. When the shaft 500 passes out of the delivery assembly 400, the shaft 500 assumes the preset configuration. The flexible shaft 500 can be made, in whole or in part, of one or more metals, alloys (e.g., steel alloys such as stainless steel), plastics, polymers, and combinations thereof, as well as other biocompatible materials.

In some embodiments, the shaft 500 selectively moves between a delivery configuration and a treatment configuration. For example, the shaft 500 can have a substantially straight configuration for delivery and a curved configuration for engaging tissue. In such embodiments, the shaft 500 can be made, in whole or in part, of one or more shape memory materials, which move the shaft 500 between the delivery configuration and the treatment configuration when activated. Shape memory materials include, for example, shape memory alloys (e.g., NiTi), shape memory polymers, ferromagnetic materials, and the like. These materials can be transformed from a first preset configuration to a second preset configuration when activated (e.g., thermally activated).

The ablation assembly 520 includes a protective section 524 and an ablation element 525. When the ablation element 525 is activated, the ablation element 525 outputs energy to targeted tissue. The protective section 524 inhibits or blocks the outputted energy to protect non-targeted tissue. The ablation element 525 and the protective section 524 thus cooperate to provide localized delivery of energy to minimize, limit, or substantially eliminate unwanted ancillary trauma associated with the outputted energy.

The ablation element 525 can be adapted to output energy that ablates tissue. The terms “ablate” or “ablation,” including derivatives thereof, include, without limitation, substantial altering of electrical properties, mechanical properties, chemical properties, or other properties of tissue. In the context of pulmonary ablation applications shown and described with reference to the variations of the illustrative embodiments herein, “ablation” includes sufficiently altering of nerve tissue properties to substantially block transmission of electrical signals through the ablated nerve tissue.

The term “element” within the context of “ablation element” includes a discrete element, such as an electrode, or a plurality of discrete elements, such as a plurality of spaced apart electrodes, which are positioned so as to collectively treat a region of tissue or treat discrete sites. One type of ablation element emits energy that ablates tissue when the element is coupled to and energized by an energy source. Example energy emitting ablation elements include, without limitation, electrode elements coupleable to direct current (“DC”) sources or alternating current (“AC”) sources (e.g., radiofrequency (“RF”) current sources), antenna elements energizable by microwave energy sources, pulsed high voltage sources, heating elements (e.g., metallic elements or other thermal conductors which are energized to emit heat via convective heat transfer, conductive heat transfer, etc.), light emitting elements (e.g., fiber optics capable of transmitting light sufficient to ablate tissue when the fiber optics are coupled to a light source), light sources (e.g., lasers, light emitting diodes, etc.), ultrasonic elements such as ultrasound elements adapted to emit ultrasonic sound waves sufficient to ablate tissue when coupled to suitable excitation sources), combinations thereof, and the like.

As used herein, the term “ablate,” including variations thereof, is construed to include, without limitation, to destroy or to permanently damage, injure, or traumatize tissue. For example, ablation may include localized tissue destruction, cell lysis, cell size reduction, necrosis, or combinations thereof.

In some embodiments, the ablation assembly 520 can be connected to an energy generator (e.g., a radiofrequency (RF) electrical generator) by electrical cables within the shaft 500. For example, the RF electrical generator can be incorporated into the controller 202 of FIG. 2A. In some embodiments, the RF electrical generator is incorporated into the ablation assembly 520.

RF energy can be outputted at a desired frequency based on the treatment. Example frequencies include, without limitation, frequencies in the range of about 50 KHZ to about 1000 MHZ. When the RF energy is directed into tissue, the energy is converted within the tissue into heat causing the temperature of the tissue to be in the range of about 40° C. to about 99° C. The RF energy can be applied for a length of time in the range of about 1 second to about 120 seconds. In some embodiments, the RF generator has a single channel and delivers approximately 1 to 25 watts of RF energy and possesses continuous flow capability. Other ranges of frequencies, time internals, and power outputs can also be used.

The protective section 524 can be in the form of a shield made, in whole or in part, of a material that is non-transmissive with respect to the energy from the ablation element 525. In some embodiments, the protective section 524 is comprised of one or more metals, optically opaque materials, and the like. If the ablation element 525 outputs ablative energy, the protective section 524 can block a sufficient amount of the ablative energy to prevent ablation of tissue directly next to the protective section 524. In this manner, non-targeted tissue is not permanently damaged.

A user can visually inspect the airway 100 using the delivery assembly 400 of FIGS. 5A and 5B to locate and evaluate the treatment site(s) and non-targeted tissues before, during, and/or after performing a therapy. The delivery assembly 400 can be a catheter, delivery sheath, bronchoscope, endoscope, or other suitable device for guiding the elongate assembly 200A. In some embodiments, the delivery assembly 400 includes one or more viewing devices, such as optical viewing devices (e.g., cameras), optical trains (e.g., a set of lens), and the like. For example, the delivery assembly 400 can be in the form of a bronchoscope having one or more lights for illumination and optical fibers for transmitting images. By way of another example, the delivery assembly 400 can have an ultrasound viewing device, as discussed in connection with FIGS. 11A and 11B.

FIGS. 6-9 show one exemplary method of using the treatment system 198A. Generally, the treatment system 198A can alter nerve tissue of the airway 100 to control nervous system input to a portion of the lung while not damaging to any significant extent other pulmonary structures.

As shown in FIG. 6, the delivery assembly 400 is moved along the lumen 101 of the airway 100, as indicated by an arrow 560. The elongate assembly 200A is carried in the delivery assembly 400 to prevent injury to the airway 100 during positioning of the delivery assembly 400.

FIG. 7 shows the elongate assembly 200A moving along the lumen 401 towards an opening 564, as indicated by an arrow 568. While the elongate assembly 200A is moved through the delivery assembly 400 (shown in cross-section), the ablation assembly 520 (shown in phantom) can be housed within the shaft 500 to prevent damage to the airway 100 or the delivery assembly 400, or both. A user can push the shaft 500 out of the delivery assembly 400 towards the airway wall 103.

FIG. 8 shows a distal end 570 of the shaft 500 proximate to the wall 103. The sharp ablation assembly 520 is deployed from the shaft 500 and contacts the wall 103. The ablation assembly 520 is then advanced through the wall 103 until the exposed ablation element 525 is embedded within the wall 103, as shown in FIG. 9. The position of the ablation assembly 520 relative to the airway wall 103 can be adjusted by extending or retracting the ablation assembly 520. Because the ablation assembly 520 is relatively slender, the wall 103 can experience an insignificant amount of trauma.

The illustrated ablation assembly 520 is connected to one lead of the RF generator and the other lead of the RF generator may be connected to an external electrode. When the RF generator is activated, the ablation element 525 delivers RF energy to tissue contacting or adjacent to the ablation element 525. RF energy flows through the tissue and is converted into heat. The heat can be concentrated in the outer portion of the airway wall 103. For example, the ablation element 525 of FIG. 5B outputs RF energy that causes damage to the nerve trunks 45. In some embodiments, a sufficient amount of RF energy is delivered to the nerve trunk 45 to destroy an entire longitudinal section of the nerve trunk 45 while keeping the amount energy that reaches the blood vessels 130 below an amount that causes tissue destruction. Damage to other non-targeted regions (e.g., the epithelium) can also be kept at or below an acceptable level. Thus, therapies can be performed without damaging to any significant extent other regions of the airway 100, even regions that are adjacent to the treatment site.

Natural body functions can help prevent, reduce, or limit damage to tissue. If the bronchial artery branches 130 are heated by the treatment system 198A, blood within the blood vessels 130 can absorb the thermal energy and can then carry the thermal energy away from the heated section of the branches 130. In this manner, thermal energy is transferred to the blood. After the treatment is performed, the bronchial artery branches 130 can continue to maintain the health of lung tissue.

This procedure may be repeated to damage additional tissue of nerve trunks 45 located outside the circumference of the wall 103. In some embodiments, all the nerves about the airway 100 can be treated to prevent signals from passing between a proximal section 571 of the airway 100 and distal section 573 of the airway 100, as shown in FIG. 5A. Because signals are not transmitted to the distal section 573, the distal section 573 can dilate. The airway 100 can also remain generally intact to maintain the health of the distal section 573. Upon completion of the treatment process, the ablation assembly 520 is retracted back into the shaft 500 for removal from the airway 100 or for placement at other treatment locations.

Treatment efficacy can be evaluated based at least in part on one or more airway attributes, pulmonary function tests, exercise capacity tests, and/or questionnaires. Patients can be evaluated to track and monitor their progress. If needed or desired, additional procedures can be performed until desired responses are achieved.

Different types of instruments for evaluating airway attributes may be used with treatment systems. During ablation, feedback from an instrument can indicate whether the targeted tissue has been ablated. Once targeted tissue is ablated, therapy can be discontinued to minimize or limit collateral damage, if any, to healthy untargeted tissue. FIG. 2B shows an instrument 199 with a detection element in the form of a balloon. Fluid (e.g., air, saline solution, or the like) can be used inflate the balloon to evaluate airway attributes. The instrument 199 can be a conventional instrument for airway dilation, airway occlusion, or the like. Instruments available for purchase from numerous medical suppliers, including Ackrad Laboratories, Cranford, N.J. and Erich Jaeger, Hoechberg, Germany, can be used with, or modified to be used with, the treatments systems disclosed herein. The instruments can be delivered through the treatment systems (e.g., through a central lumen of the treatment system) to position a detection element distal to the treatment system.

The attributes of airways evaluated by the instrument may include, without limitation, physical properties of airways (e.g., airway compliance, contractile properties, etc.), airway resistance, dimensions of airway lumens (e.g., shapes of airways, diameters of airways, etc.), responsiveness of airways (e.g., responsiveness to stimulation), muscle characteristics (e.g., muscle tone, muscle tension, etc.), or the like. In some embodiments, changes of airway muscle characteristics can be monitored by measuring pressure changes the intraluminal balloon that is inflated to a known pressure. Based on pressure changes in the balloon, a physician determines the effects, if any, of the treatment, including, without limitation, whether targeted tissue has been stimulated, damaged, ablated, or the like. For example, the balloon can be positioned distal to the targeted tissue. As nerve tissue is damaged, muscle tension in the airway surrounding the balloon is reduced causing expansion of the airway, as well as expansion of the balloon. The pressure in the balloon decreases as the balloon expands.

The instrument 199 and the treatment system 198 can be delivered through different lumens in a delivery device, including, without limitation, a multi-lumen catheter, a delivery sheath, bronchoscope, an endoscope, or other suitable device for delivering and guiding multiple devices. The delivery device can be selected based on the location of the treatment site(s), configuration of the treatment system, or the like.

Decreases in airway resistance may indicate that passageways of airways are opening, for example, in response to attenuation of nervous system input to those airways. The decrease of airway resistance associated with treating low generation airways (e.g., main bronchi, lobar bronchi, segmental bronchi) may be greater than the amount of decrease of airway resistance associated with treating high generation airways (e.g., subsegmental bronchioles). A physician can select appropriate airways for treatment to achieve a desired decrease in airway resistance and can be measured at a patient's mouth, a bronchial branch that is proximate to the treatment site, a trachea, or any other suitable location. The airway resistance can be measured before performing the therapy, during the therapy, and/or after the therapy. In some embodiments, airway resistance is measured at a location within the bronchial tree by, for example, using a vented treatment system that allows for respiration from areas that are more distal to the treatment site.

FIGS. 10A-14B illustrate treatment assemblies that can be generally similar to the treatment assembly 198A discussed in connection with FIGS. 5A-9, except as detailed below. FIG. 10A illustrates a treatment system 198B that includes an elongate assembly 200B. The elongate assembly 200B includes an elongate flexible shaft 610 and a plurality of radially deployable ablation assemblies 620. The ablation assemblies 620 can be collapsed inwardly when the shaft 610 is pulled proximally through the delivery assembly 400 (shown in cross-section). When the plurality of ablation assemblies 620 is pushed out of the delivery assembly 400, the ablation assemblies 620 self-expand by biasing radially outward.

Each electrode assembly 620 includes a sharp tip for piercing the airway wall 103 and includes extendable and retractable sharp ablation elements 625. The ablation assemblies 620 are preferably insulated except for the exposed ablation elements 625. The ablation assemblies 620 can be connected to a RF electrical generator by electrical cables that travel within the shaft 610. While the treatment system 198B is being delivered, the ablation assemblies 620 may be positioned within the shaft 610. The ablation assemblies 620 can be moved out of the shaft 610 and brought into contact with the wall 103. The ablation assemblies 620 can be simultaneously moved through the airway wall 103 until desired lengths of the ablation elements 625 are within the airway wall 103.

As shown in FIG. 10B, the plurality of ablation elements 625, illustrated as electrodes, may be circumferentially spaced from each other along the airway wall 103. The ablation elements 625 can be evenly or unevenly spaced from one another.

All of the ablation assemblies 620 can be connected to one lead of the RF generator and the other lead of the RF generator may be connected to an external electrode 623 (shown in phantom), so that current flows between the ablation assemblies 620 and/or between one or more of the ablation assemblies 620 and the external electrode 623. In some embodiments, a selected number of the ablation assemblies 620 are connect to one lead of the RF generator while the other ablation assemblies 620 are connected to the other lead of the RF generator such that current flows between the ablation assemblies 620.

When the RF generator is activated, current flows through the tissue and generates a desired amount of heat. The heat can be concentrated on the outside of the airway wall 103 to damage peripheral tissue. For example, the temperature of the connective tissue can be higher than the temperatures of the stroma, smooth muscles, and/or the epithelium. By way of example, the temperature of the connective tissue can be sufficiently high to cause damage to the nerve tissues in the nerve trunks 45 while other non-targeted tissues of the airway 100 are kept at a lower temperature to prevent or limit damage to the non-targeted tissues. In other embodiments, heat can be concentrated in one or more of the internal layers (e.g., the stroma) of the airway wall 103 or in the inner periphery (e.g., the epithelium) of the airway wall 103.

As shown in FIG. 10B, one or more vessels of the bronchial artery branches 130 may be relatively close to the ablation elements 625. The heat generated by the ablation elements 625 can be controlled such that that blood flowing through the bronchial artery branches 130 protects the those branches 130 from thermal injury while nerve tissue is damaged, even if the nerve tissue is next to the artery branches 130. Upon completion of the treatment process, the ablation assemblies 620 are retracted back into the shaft 610 for removal from the airway 100 or for placement at other treatment locations.

FIGS. 11A and 11B illustrate a treatment system 198C that includes an elongate assembly 200C. The elongate assembly 200C includes an elongate flexible shaft 710 and a plurality of extendable and retractable ablation assemblies 720. When the ablation assemblies 720 are deployed, the ablation assemblies 720 bias radially outward and into contact with a tubular section 719 of the airway 100. Ablation elements 725 of the ablation assemblies 720 can be axially and circumferentially distributed throughout a treatment length L_(T) of the section 719.

The ablation assemblies 720 can include protective sections 721 and the exposed ablation elements 725. The protective sections 721 can extend from the shaft 710 to an inner surface of the airway 100. The ablation elements 725 protrude from corresponding protective sections 721. The ablation assemblies 720 can be connected to a radiofrequency (RF) electrical generator by electrical cables that travel within the shaft 710.

The treatment system 198C is delivered to the desired treatment location within the airway 100. While the treatment system 198C is being delivered, the ablation assemblies 720 are retracted within the shaft 710 so as not to damage the airway 100 or the delivery device 400, or both. Once in position, the sharp ablation elements 725 are brought into contact with the airway wall 103. The elements 725 are then advanced through the airway wall 103 until the ablation elements 625 are embedded within the airway wall 103. Substantially all of the ablation assemblies 720 can be connected to one lead of the RF generator and the other lead of the RF generator may be connected to an external electrode, so that current flows between the ablation assemblies 720 and the external electrode. Alternatively, selected individual ablation assemblies 720 can be connect to one lead of the RF generator while other ablation assemblies 720 can be connected to the other lead of the RF generator, so that current can flow between the ablation assemblies 720.

FIG. 12A illustrates the elongate assembly 200A of FIGS. 5A and 5B passing through a delivery assembly 400A, illustrated as a bronchoscope, that has an imaging device 850. The imaging device 850 is positioned at a tip 413A of the delivery assembly 400A. In some embodiments, the imaging device 850 includes an array of ultrasound transducers with a working frequency between about 1 MHz to about 250 MHz and Doppler capabilities. Wavefronts 860 outputted by the imaging device 850 are illustrated in FIGS. 12A and 12B.

When used, the delivery device 400A is advanced to the desired treatment region of the airway 100. The imaging device 850 is then used to image at least a portion of the airway wall 103, thereby locating the anatomical structures, such as the nerve trunks 45 and/or bronchial artery branches 130, which are located in the connective tissue 124 outside of the airway wall. For example, the imaging device 850 can be used to circumferentially image the airway 100. In some modes of operation, target tissues (e.g., the nerve trunks 45, mucous glands 116, and the like) are located such that only the portion of the wall 103 immediately adjacent to the target tissues and the connective tissue 124 are treated. In other modes of operation, the non-targeted tissues (e.g., bronchial artery branches 130) are localized and all other regions of the wall 103 and the connective tissue 124 are treated.

When treating the nerve trunks 45, the tip 413 of the delivery device 400A can be guided and positioned near a selected nerve trunk 45. Once in position, the sharp ablation element 525 is brought into contact with the wall 103. The ablation element 525 is then advanced through the wall 103 until the ablation elements 525 are embedded. The illustrated exposed ablation elements 525 are adjacent to the nerve trunk in the connective tissue 124. The RF generator is activated and current flows between the ablation assembly 520 and the tissue of the wall 103. The current causes the tissues of the nerve trunks 45 to increase in temperature until the heated tissue is damaged. By positioning the ablation assembly 520 near the nerve trunk 45, the nerve trunk 45 is selectively damaged while injury to non-targeted tissues, such as the bronchial arteries 130, is minimized. This procedure may be repeated to damage additional nerve branches 45 located around the circumference of the wall 103 in or adjacent to the connective tissue 124.

Various types of devices can be used to remotely treat target tissues. FIGS. 13A and 13B illustrate a treatment system 200E in the form of a bronchoscope having high energy ultrasound transducer array 950 located at its tip 413E. The energy ultrasound transducer array 950 can be positioned to image the desired treatment site. The ultrasound transducer array 950 is then used to circumferentially image the wall 103 to localize the nerve trunks 45 and/or the bronchial arteries 130. In some modes of operation, the nerve trunks 45 are localized and only the area of the wall 103 of the airway 100 and the connective tissue 124 around the nerve trunks 45 is treated using ultrasound energy. In other modes of operation, the bronchial arteries 130 are localized and all other areas of the wall 103 of the airway 100 and the connective tissue 124 are treated using ultrasound energy.

The ultrasound transducer array 950 can emit highly focused sound waves 960 into the connective tissue 124 to damage the nerve trunks 45 and minimize or prevent injury to the bronchial arteries 130. The tip 413E of the bronchoscope 400B can be positioned such that the outputted energy is directed away from or does not reach the bronchial artery branches 130. This procedure of remotely treating tissue may be repeated to damage additional nerve trunks 45 located around the circumference of the wall 103 in the connective tissue 124, as desired. The bronchoscope 400B can be used to damage all or at least some of the nerve trunks 45 at a particular section of the airway 100.

FIGS. 14A and 14B illustrate a treatment system 198F that includes an elongate assembly 200F. The elongate assembly 200F includes an elongated shaft 1110 and an extendable and retractable puncturing tip 1120. The puncturing tip 1120 is adapted to pass through tissue and includes at least one port 1130. The illustrated puncturing tip 1120 includes a single side port 1130 for outputting flowable substances. A lumen can extend proximally from the port 1130 through the shaft 1110. A flowable substance can flow distally through the lumen and out of the port 1130. Example flowable substances include, without limitation, one or more heated liquids, cooled liquids, heated gases, cooled gases, chemical solutions, drugs, and the like, as well as other substances that that can cause damage to tissue. For example, saline (e.g., heated or cooled saline) or cryogenic fluids can be delivered through the port 1130.

The elongate assembly 200F of FIGS. 14A and 14B can be delivered to the desired treatment location using the delivery assembly 400. While the elongate assembly 200F is being delivered, the puncturing tip 1120 is retracted within the shaft 1110 so as to not damage the airway 100 and/or the delivery assembly 400. Once in position, the sharp hollow tip 1020 is brought into contact with the airway wall 103. The tip 1020 is then advanced through the airway wall 103 until the side port 1130 is within or adjacent to the connective tissue 124. The flowable substance is delivered through the tip 1020 and out of the port 1130 and flows against the tissue of the airway 100. In some embodiments, the expelled substance cuts, crushes, or otherwise damages the tissue. In some embodiments, the flowable substance includes at least one long acting nerve blocking drug that partially or completely blocks nerve conduction in the nerve trunks 45.

FIGS. 15A-19B illustrate treatment systems that can be generally similar to the treatment system 198A discussed in connection with FIGS. 5A-9, except as detailed below. FIG. 15A is a longitudinal side view of a treatment system 2000 in the form of a balloon expandable, fluid heated/cooled electrode catheter. FIG. 15B is a cross-sectional view of an expandable assembly 2001 of the system 2000. The illustrated expandable assembly 2001 is in an expanded state. Lines of flow 2100 represent the movement of fluid through the expanded assembly 2001. The expanded assembly 2001 includes an expandable member 2002 and an ablation electrode 2004. The ablation electrode 2004 can be collapsed inwardly when the treatment system 2000 is moved (e.g., pulled proximally or pushed distally) through a delivery assembly. When the treatment system 2000 is pushed out of the delivery assembly, the ablation electrode 2004 can be expanded outward by inflating the expandable member 2002.

The treatment system 2000 generally includes the expandable member 2002 (illustrated in the form of a distensible, thermally conductive balloon), an ablation electrode 2004, a conducting element 2031, an inflow line 2011, and an outflow line 2021. The ablation electrode 2004 is expandable and connected to a distal end 2033 of the conducting element 2031. A proximal end 2035 of the conducting element 2031 is connected to an electrical connector 2038. Energy is transferred from the electrical connector 2038 to the expandable electrode 2004 through the conducting element 2031. The conducting element 2031 can include, without limitation, one or more wires, conduits, or the like.

A proximal end 2009 of the inflow line 2011 has an inline valve 2012. A proximal end 2015 of the outflow line 2021 also has an outflow valve 2022. The inline valve 2011 can be connected to a fluid supply, such as a coolant source, by a connector 2018. Fluid flows through the inflow line 2011 into the balloon 2002, and exits the balloon 2002 via the outflow line 2021. The fluid can include, without limitation, temperature controlled fluid, such as water, saline, or other fluid suitable for use in a patient.

A lumen 2017 of the inflow line 2011 and a lumen 2019 of the outflow line 2021 provide fluid communication with the balloon 2002. Fluid can flow through the lumen 2017 into the balloon 2002. The fluid circulates within the balloon 2002 and flows out of the balloon 2002 via the lumen 2019. The fluid can pass through the connector 2028 to a fluid return system, which may cool the fluid and re-circulate the fluid to the fluid supply.

Different types of materials can be used to form different components of the system 2000. In some embodiments, the balloon 2002 is made, in whole or in part, of a distensible, chemically inert, non-toxic, electrically insulating, and thermally conductive material. For example, the balloon 2002 may be made of polymers, plastics, silicon, rubber, polyethylene, combinations thereof, or the like. In some embodiments, the inflow line 2011 and the outflow line 2021 are made, in whole or in part, of any suitable flexible, chemically inert, non-toxic material for withstanding operating pressures without significant expansion. The inflow line 2011 and the outflow line 2021 can have a suitable length to be passed into the lung and bronchial tree. For example, the lines 2011, 2021 can have a length of approximately 80 cm. Other lengths are also possible.

FIG. 15B shows the inflow line 2011 and the outflow line 2021 arranged to minimize, reduce, or substantially prevent cross flow, siphoning, or back flow between the two lines 2011, 2021. The illustrated inflow line 2011 carries the balloon 2004. The inflow line 2011 can enter a proximal end 2003 of the balloon 2002, extend through the length of the balloon 2002, and reach a distal end 2007 of the balloon 2002. The illustrated inflow line 2011 is connected to the distal end 2007 to keep the balloon 2002 in an elongated configuration.

A tip 2005 protrudes from the balloon 2002. The illustrated tip 2005 is an atruamatic tip positioned opposite the end of the inflow line 2011. Near the tip 2005, the inflow line 2011 has an aperture 2013 that releases fluid into the balloon 2002. The fluid flows within the balloon 2002 and is collected into the outflow line 2021. The illustrated outflow line 2021 has an opening 2023 for receiving the fluid. The opening 2023 is generally at the distal end of a portion of the outflow line 2021 in the balloon 2002 and collects fluid from any direction. Because the openings 2013, 2023 are at opposite ends of the balloon 2002, fluid can flow in generally one direction through the balloon 2002. This ensures that fluid at a desired temperature fills the balloon 2002.

The shapes of the electrode 2004 and the balloon 2002 can be selected such that the electrode 2004 and balloon 2004 expand/deflate together. When the balloon 2002 is inflated, the electrode 2004 is expanded with the balloon 2002. When the balloon 2002 is deflated, the electrode 2004 contracts with the balloon 2002. The electrode 2004 may be coupled to an exterior surface or interior surface of the balloon 2002 and may be made of different types of conductive materials, including, without limitation, any chemically inert, non-toxic, structurally resilient, electrically conducting material. In some embodiments, the electrode 2004 is coupled to the exterior of the balloon 2002 and made, in whole or in part, of a highly conductive, deformable material. Energy outputted by the electrode 2004 is outputted directly into the airway wall 100 without passing through the wall of the balloon 2002. The electrode 2004 can be a thin wire or band made mostly or entirely of copper. The wire can be coated or uncoated depending on the application. In other embodiments, the electrode 2004 is embedded in the wall of the balloon 2002. Any number of electrodes 2004 can be positioned along the balloon 2002. For example, an array of spaced apart electrodes can be positioned along the balloon to treat a length of an airway.

The electrical conducting element 2031 travels along side and generally parallel to one or both of the lines 2011, 2021. The electrode 2004 can be connected through the electrical conducting element 2031 and the electrical connector 2038 to an energy source, such as an RF electrical generator. If the energy source is an RF electrical generator, one lead can be coupled to the connector 2038. The other lead of the RF generator may be connected to an external electrode, such as the external electrode 623 shown in phantom in FIG. 10B, so that current flows between the expandable electrode 2004 and the external electrode.

The balloon expandable, fluid cooled electrode catheter 2000 can be delivered into the airways of the lung with the balloon 2002 deflated and the electrode 2004 contracted. The electrode 2004 can be kept in a collapsed or closed configuration to allow the catheter 2000 to pass easily through the lungs. The catheter 2000 is moved through the airways until the electrode 2004 is at the desired treatment location. Once in position, fluid (e.g., coolant) is allowed to flow through the inflow line 2011 and into the balloon 2002. The fluid inflates the balloon 2002 which in turn expands the electrode 2004. Outflow of the fluid through the outflow line 2021 can be regulated such that the balloon 2002 continues to inflate until the electrode 2004 is brought into contact with or proximate to the airway wall.

Treatment can begin with activation of the RF generator. When the RF generator is activated, RF energy is transmitted through the electrical connector 2038, through the electrical connection element 2031, through the expanded electrode 2004, and into the tissues of the airways. The RF energy heats tissue (e.g., superficial and deep tissue) of the airway wall and the fluid 2100 (e.g., a coolant) flowing through the balloon 2002 cools tissue (e.g., superficial tissues) of the airway wall. The net effect of this superficial and deep heating by RF energy and superficial cooling by the circulating coolant 2100 through the balloon 2002 is the concentration of heat in the outer layers of the airway wall 100. The coolant can be a chilled liquid. The temperature of the connective tissue can be higher than the temperatures of the epithelium, stroma, and/or smooth muscle. By example, the temperature of the connective tissue can be sufficiently high to cause damage to the nerve trunk tissue while other non-targeted tissues of the airway are kept at a lower temperature to prevent or limit damage to the non-targeted tissues. In other embodiments, heat can be concentrated in one or more of the internal layers (e.g., the stroma) of the airway wall or in the inner lining (e.g., the epithelium) of the airway wall.

FIGS. 16 and 17 show the effect produced by superficial and deep heating by RF energy and superficial cooling by circulating coolant 2100 in the balloon 2002. FIG. 16 shows a cross-sectional temperature profile taken along a dashed line 2200 of FIG. 15B that is perpendicular to the long axis of the balloon 2002. FIGS. 16 and 17 are discussed in detail below.

FIG. 16 is a graph with a horizontal axis corresponding to the depth into the tissue of the airway wall from the point of contact or area of contact with the electrode 2004 in millimeters with a vertical axis corresponding to the temperature of the tissue in degrees Centigrade. The point “0” on the graph corresponds to the point or area of contact between the ablation electrode 2004 and the tissue of the airway wall. Three curves A, B, and C are shown in the graph and correspond to three different power levels of radio frequency energy being delivered into the tissue. The temperature on the graph is up to about 100° C. The temperature of about 100° C., or slightly less, has been shown because it is considered to be an upper limit for tissue temperature during RF ablation. At approximately 90° C., tissue fluids begin to boil and tissue coagulates and chars on the ablation electrode 2004, thereby greatly increasing its impedance and compromising its ability to transfer RF energy into the tissue of the airway wall. Thus, it may be desirable to have tissue temperatures remain below about 90° C. At about 50° C., a line 2201 represents the temperature above which tissue cell death occurs and below which tissues suffer no substantial long term effects (or any long term effects).

Curve A shown in FIG. 16 represents what occurs with and without cooling of the ablation electrode 2004 at a relatively low power level, for example, about 10 watts of RF energy. Curve A is divided into three segments A1, A2, and A3. The broken line segment A2 represents a continuation of the exponential curve A3 when no cooling applied. As can be seen by curve A, the temperature of the electrode-tissue interface without cooling reaches 80° C. and decreases exponentially as the distance into the tissue of the airway 100 increases. As shown, the curve A3 crosses the 50° C. tissue cell death boundary represented by the line 2201 at a depth of about 5 millimeters. Thus, without electrode cooling, the depth of cell death that would occur would be approximately 5 millimeters as represented by the distance d1. Further cell death would stop at this power level.

If active cooling is employed, the temperature drops to a much lower level, for example, about 35° C. as represented by the curve A1 at the electrode-tissue interface at 0 millimeters in distance. Since this temperature is below 50° C., cell death will not begin to occur until a distance of d2 at the point where the curve A2 crosses the cell death line at 50° C., for example, a depth of 3 millimeters from the surface. Cell death will occur at depths from 3 millimeters to 5 millimeters as represented by the distance d3. Such a cooled ablation procedure is advantageous because it permits cell death and tissue destruction to occur at a distance (or a range of distances) from the electrode-tissue interface without destroying the epithelium and the tissue immediately underlying the same. In some embodiments, the nerve tissues running along the outside of the airway can be ablated without damaging the epithelium or underlying structures, such as the stroma and smooth muscle cells.

The curve B represents what occurs with and without cooling of the electrode at a higher power level, for example, 20 watts of RF energy. Segment B2 of curve B represents a continuation of the exponential curve of the segment B3 without cooling. As can be seen, the temperature at the electrode-tissue interface approaches 100° C. which may be undesirable because that is a temperature at which boiling of tissue fluid and coagulation and charring of tissue at the tissue-electrode interface will occur, thus making significantly increasing the tissue impedance and compromising the ability to deliver additional RF energy into the airway wall. By providing active cooling, the curve B1 shows that the temperature at the electrode-tissue interface drops to approximately 40° C. and that cell death occurs at depths of two millimeters as represented by d4 to a depth of approximately 8 millimeters where the curve B3 crosses the 50° C. Thus, it can be seen that it is possible to provide a much deeper and larger region of cell death using the higher power level without reaching an undesirable high temperature (e.g., a temperature that would result in coagulation and charring of tissue at the electrode-tissue interface). The systems can be used to achieve cell death below the epithelia surface of the airway so that the surface need not be destroyed, thus facilitating early recovery by the patient from a treatment.

The curve C represents a still higher power level, for example, 40 watts of RF energy. The curve C includes segments C1, C2, and C3. The broken line segment C2 is a continuation of the exponential curve C3. Segment C2 shows that the temperature at the electrode-tissue interface far exceeds 100° C. and would be unsuitable without active cooling. With active cooling, the temperature at the electrode-tissue interface approaches 80° C. and gradually increases and approaches near 95° C. and then drops off exponentially to cross the 50° C. cell death line 2201 at a distance of about 15 millimeters from the electrode-tissue interface at the epithelial surface of the airway represented by the distance d6. Because the starting temperature is above the 50° C. cell death line 2201, tissue cell death will occur from the epithelial surface to a depth of about 15 millimeter to provide large and deep regions of tissue destruction.

FIG. 17 is a longitudinal cross-sectional view of the balloon expandable, fluid cooled electrode catheter 2000. Lines of flow 2100 represent the movement of coolant through the expanded balloon 2002. Isothermal curves show the temperatures that are reached at the electrode 2004 on the outer surface of the balloon 2002 and at different depths into the airway wall 100 from the electrode-tissue interface when power is applied to the electrode 2004 and coolant (e.g., a room temperature saline solution) is delivered to the balloon 2002. By adjusting the rate of power delivery to the electrode 2004, the rate at which saline solution is passed into the balloon 2002, the temperature of the saline solution, and the size of the balloon 2002, the exact contour and temperature of the individual isotherms can be modified. For example, by selecting the proper temperature and flow rate of saline and the rate of power delivery to the electrode, it is possible to achieve temperatures in which isotherm A=60° C., B=55° C., C=50° C., D=45° C., E=40° C., and F=37° C. Further adjustments make it possible to achieve temperatures where isotherm A=50° C., B=47.5° C., C=45° C., D=42.5° C., E=40° C., and F=37° C. Only those areas contained within the 50° C. isotherm will be heated enough to induce cell death. Extrapolating into 3 dimensions the isotherms shown in FIG. 17, a circumferential band 2250 of tissue will potentially be heated above 50° C. sparing the tissue near the epithelial 110 of the airway 100. Different temperatures and isotherms can also be achieved.

FIG. 18 is a transverse cross-sectional view of a portion of the airway 100 and the balloon expandable, fluid cooled electrode catheter 2000 positioned in the airway 100. Because of the undulating shape of the expandable electrode 2004, the electrode appears as a multitude of ovals. The balloon 2002 is inflated to conform to both the expandable electrode 2004 and the epithelial surface of the airway 100. The electrode 2004 can be pressed against the airway 100. When RF energy is transmitted through the expanded electrode 2004 into the tissues of the airway 100 and the balloon 2002 is filled with flowing coolant 2100, the RF energy heats the superficial and deep tissue of the airway wall 100 and the connective tissue 124 while the coolant 2100 cools the superficial tissues of the airway wall 100. The net effect of this superficial and deep heating by RF energy and superficial cooling by the circulating coolant 2100 is the concentration of heat in the outer layers of the airway wall 100, such as the connective tissue 124. A band 2250 of tissue can be selectively heated above 50° C. For example, the temperature of the connective tissue 124 can be higher than the temperatures of the epithelium 110, stroma 112, and/or smooth muscle 114. Furthermore, one or more of the vessels of the bronchial artery branches 130 may be within the band 2250. The heat generated using the electrode 2004 can be controlled such that blood flowing through the bronchial artery branches 130 protects those branches 130 from thermal injury while nerve trunk tissue 45 is damaged, even if the nerve tissue is next to the artery branches.

The electrode catheter 2000 can treat tissue without forming an airway wall perforation at the treatment site to prevent or reduce the frequency of infections. It may also facilitate faster healing for the patient of tissue proximate the region of cell death. The catheter 2000 can produce relatively small regions of cell death. For example, a 2 to 3 millimeter band of tissue in the middle of the airway wall 100 or along the outer surface of the airway wall 100 can be destroyed. By the appropriate application of power and the appropriate removal of heat from the electrode, lesions can be created at any desired depth without damaging the inner surface of the airway.

Upon completion of the treatment process, coolant inflow into the balloon 2002 can be stopped. The balloon 2002 is deflated causing the expandable electrode 2004 to recoil away from the airway wall 100. When the balloon 2002 is completely deflated, the balloon expandable, fluid cooled electrode catheter 2000 may be repositioned for treating other locations in the lung or removed from the airway 100 entirely.

FIGS. 19A and 19B illustrate a treatment system that can be generally similar to the catheter 2000 discussed in connection with FIGS. 15A-18. A balloon expandable, fluid heat-sink electrode catheter 2500 has a single coolant line 2511 with associated inline valve 2512 and connector 2518 that provide for alternately inflow and outflow of heat-sink fluid into and out of a balloon 2502.

The balloon expandable, fluid heat-sink electrode catheter 2500 can be delivered into the airways of the lung with the balloon 2502 deflated and the electrode 2504 contracted. The catheter 2500 can be moved within the airways until the electrode 2504 is in a desired treatment location. Once in position, heat-sink fluid is passed through the line 2511 and into the balloon 2502, thereby inflating the balloon 2502 and expanding the electrode 2504. The fluid is passed into the balloon 2502 until the electrode 2504 is brought into contact with the airway wall 100.

The heat-sink fluid passed into the balloon 2502 of electrode catheter 2500 is generally static and acts as a heat-sink to stabilize the temperature of the electrode 2504 and the superficial tissues of the airway wall 100. The static heat sink provided by the fluid in the balloon 2502 can produce temperature profiles and isotherms similar to those shown in FIGS. 16 and 17. For example, the electrode catheter 2500 can cause a band of tissue cell death in the connective tissue of the airway while the epithelium, stroma, and/or smooth muscle are relatively undamaged. Thus, the nerve tissue can be damaged while other non-targeted tissues of the airway are protected.

FIGS. 20A-21 illustrate a treatment system that can be generally similar to the balloon expandable, fluid cooled electrode catheter 2000 shown in FIGS. 15A-18. FIG. 20A is a longitudinal side view of a radial ultrasound guided fluid cooled electrode catheter 3000. FIG. 20B is a partial longitudinal sectional view of the radial ultrasound guided fluid cooled electrode catheter 3000 taken through a balloon 3002 with lines of flow 3100 representing the movement of coolant through the expanded balloon 3002 and wavefronts 3047 of ultrasound imaging for guiding the ablation device.

The electrode catheter 3000 generally includes a distensible, thermally conductive balloon 3002, an electrode 3004, a conducting element 3031, an inflow line 3011, an outflow line 3021, and an ultrasound probe 3045. The expandable electrode 3004 is connected to a distal end of the conducting element 3031. A proximal end of the conducting element 3031 is connected to an electrical connector 3038 for transmission of energy (e.g., RF energy) to the electrode 3004. The proximal end of the coolant inflow line 3011 has an inline valve 3012. The proximal end of the coolant outflow line 3021 also has an outline valve 3022. The inflow valve 3012 can be connected to a coolant source by the connector 3018. The lumen of the inflow line 3011 and the lumen of the outflow line 3021 provide for fluid to flow from the fluid source to the inside of the balloon 3002 and for fluid flow through another connector 3028 to the coolant return, where the coolant may be re-cooled and re-circulated to the fluid supply.

The inflow line 3011 and outflow line 3021 have a suitable length to be passed into the lung and bronchial tree. For example, the catheter 3000 can have a length of approximately 80 cm. FIG. 20B shows a catheter 3000 is adapted to reduce, limit, or substantially prevent cross-flow, siphoning, or back-flow between the two lines within the balloon 3002. The inflow line 3011 enters the proximal end of the balloon 3002, extends through the length of the balloon 3002, reaches the distal end of the balloon 3002, and connects to the balloon 3002. The inflow line 3011 has an aperture 3013 near a tip 3005 that releases coolant into the balloon 3002. The fluid flows within the balloon 3002 and then is collected into the outflow line 3021 via an opening 3023. The opening 3023 is generally at the distal end of the outflow line 3021 and collects coolant from any direction.

The electrode 3004 is located on a surface of the balloon 3002 such that, when the balloon 3002 is inflated using fluid, the electrode 3004 is brought into contact with the airway wall 100. The electrical conducting element 3031 travels along side and parallel to the inflow line 3011, the outflow line 3021, and the ultrasound sheath 3041. The electrode 3004 can be connected through the electrical conducting element 3031 and the electrical connector 3038 to an RF generator. The other lead of the RF generator may be connected to an external electrode so that current flows between the expandable electrode 3004 and the external electrode.

The ultrasound probe 3045 may be an integral part of the ultrasound guided fluid cooled electrode catheter 3000 or it may be a separate, standard radial ultrasound probe, such as an Olympus UM-2R-3 or UM-3R-3 probe driven by a standard Olympus processor EU-M60, with the radial ultrasound guided fluid cooled electrode catheter 3000 configured to slip over the standard radial ultrasound probe.

The ultrasound system can include a broadband ultrasound transducer operating with a center frequency between about 7 MHz and about 50 MHz. If the ultrasound probe 3045 is an integral part of the electrode catheter 3000, the ultrasound probe 3045 may be contained within an acoustically matched ultrasound cover 3041 and connected to an ultrasound drive unit and processor by the ultrasound connector 3048. In operation, the ultrasound probe 3045 is rotated about its longitudinal axis within the ultrasound cover 3041 by the ultrasound drive unit and processor through the ultrasound connector 3048 allowing images (e.g., 360° radial images) to be taken. These images can be taken in a direction perpendicular to the long axis of the ultrasound probe 3045. The fluid in the balloon 3002 can acoustically couple the ultrasound probe 3045 to the airway wall.

The electrode catheter 3000 can be delivered into the airways of the lung with the balloon 3002 in a deflated state. The catheter 3000 is positioned within the airways near or at the desired treatment location. Once positioned, fluid flows through the inflow line 3011 and into the balloon 3002. The balloon 3002 inflates to bring the electrode 3004 into contact with the epithelial surface of the airway. Outflow of fluid through the outflow line 3021 can be regulated such that the balloon 3002 continues to inflate until the electrode 3004 is brought into contact with the airway wall 100.

The ultrasound drive unit and processor can be activated. The ultrasound probe 3045 can capture images. For example, the probe 3045, within the ultrasound cover 3041, can be rotated about its longitudinal axis to produce 360° radial images of the airway and vessels airway wall structures. The electrical connection wire 3031 can serve as a guide on the ultrasound images to the location of the electrode 3004. A section of the wire 3031 extending along (e.g., over the surface) of the balloon 3002 can be visible in the ultrasound images. The section of wire 3031 can therefore indicate the location of the electrode 3004. In some embodiments, the nerve trunks and bronchial blood can be identified in the ultrasound images and the ultrasound guided fluid cooled electrode catheter 3000 can be rotated until the electrode 3004 is brought into proximity with the first nerve trunk 45.

When the RF generator is activated, RF energy is transmitted by the generator through the electrical connector 3038, through the electrical connection wire 3031, through the expanded electrode 3004, and into the tissues of the airways. The RF energy heats the superficial and deep tissue of the airway wall 100 and the connective tissue 124 in the area immediately overlying the electrode 3004 and the coolant flowing 3100 through the balloon 3002 cools the superficial tissues of the airway wall 100. The net effect of this superficial and deep heating by RF energy and superficial cooling by the circulating coolant 3100 through the balloon 3002 is the concentration of heat in the outer layers of the airway wall 100 immediately overlying the electrode 3004. For example, the temperature of the connective tissue 124 in the area of a single nerve trunk 45 can be higher than the temperatures of the epithelium 110, stroma 112, and/or smooth muscle 114. By example, the temperature of the connective tissue can be sufficiently high to cause damage to the nerve tissue 45 while other non-targeted tissues of the airway 100 are kept at a lower temperature to prevent or limit damage to the non-targeted tissues. The treatment can be repeated in other areas as needed.

FIG. 21 is a transverse cross-sectional view of a portion of the airway 100 and the ultrasound guided fluid cooled electrode catheter 3000 positioned in the airway 100. The cross-section is taken through the electrode 3004 itself.

The balloon 3002 is conformable to both the electrode 3004 and the epithelial surface of the airway 100. When RF energy is transmitted through the electrode 3004 into the tissues of the airways and the balloon 3002 is filled with flowing coolant 3100, the RF energy heats the superficial and deep tissue of the airway wall 100 immediately overlying the electrode 3004. The coolant 3100 flows to control the temperature of the superficial tissues of the airway wall 100. The net effect is the concentration of heat in the outer layers of the airway wall 100 immediately over the electrode 3004 producing a single target volume 3250 of tissue heated above a treatment temperature (e.g., about 50° C.). For example, the temperature of the connective tissue 124 in the region of a single nerve trunk 45 in the region immediately over the electrode 3004 can be higher than the temperatures of the epithelium 110, stroma 112, and/or smooth muscle 114.

The vessels of the bronchial artery branches 130 may be within or near the volume of heating produced during application of RF energy. The heat generated by the electrode 3004 can be controlled such that blood flowing through the bronchial artery branches 130 protects those branches 130 from thermal injury while nerve tissue 45 is damaged, even if the nerve tissue is next to the artery branches.

The embodiments disclosed herein can be used in the respiratory system, digestive system, nervous system, vascular system, or other systems. For example, the elongate assemblies disclosed herein can be delivered through blood vessels to treat the vascular system. The treatment systems and its components disclosed herein can used as an adjunct during another medical procedure, such as minimally invasive procedures, open procedures, semi-open procedures, or other surgical procedures (e.g., lung volume reduction surgery) that preferably provide access to a desired target site. Various surgical procedures on the chest may provide access to lung tissue. Access techniques and procedures used to provide access to a target region can be performed by a surgeon and/or a robotic system. Those skilled in the art recognize that there are many different ways that a target region can be accessed.

The elongated assemblies disclosed herein can be used with guidewires, delivery sheaths, optical instruments, introducers, trocars, biopsy needles, or other suitable medical equipment. If the target treatment site is at a distant location in the patient (e.g., a treatment site near the lung root 24 of FIG. 1), a wide range of instruments and techniques can be used to access the site. The flexible elongated assemblies can be easily positioned within the patient using, for example, steerable delivery devices, such as endoscopes and bronchoscopes, as discussed above.

Semi-rigid or rigid elongated assemblies can be delivered using trocars, access ports, rigid delivery sheaths using semi-open procedures, open procedures, or other delivery tools/procedures that provide a somewhat straight delivery path. Advantageously, the semi-rigid or rigid elongated assemblies can be sufficiently rigid to access and treat remote tissue, such as the vagus nerve, nerve branches, nerve fibers, and/or nerve trunks along the airways, without delivering the elongated assemblies through the airways. The embodiments and techniques disclosed herein can be used with other procedures, such as bronchial thermoplasty.

The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. The embodiments, features, systems, devices, materials, methods and techniques described herein may, in some embodiments, be similar to any one or more of the embodiments, features, systems, devices, materials, methods and techniques described in of U.S. Provisional Patent Application No. 61/052,082 filed May 9, 2008; U.S. Provisional Patent Application No. 61/106,490 filed Oct. 17, 2008; and U.S. Provisional Patent Application No. 61/155,449 filed Feb. 25, 2009. In addition, the embodiments, features, systems, devices, materials, methods and techniques described herein may, in certain embodiments, be applied to or used in connection with any one or more of the embodiments, features, systems, devices, materials, methods and techniques disclosed in the above-mentioned of U.S. Provisional Patent Application No. 61/052,082 filed May 9, 2008; U.S. Provisional Patent Application No. 61/106,490 filed Oct. 17, 2008; and U.S. Provisional Patent Application No. 61/155,449 filed Feb. 25, 2009. Each of these applications is hereby incorporated by reference in its entirety. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure. 

What is claimed is:
 1. A system, comprising: a treatment controller; and a catheter comprising: an elongated body through which a coolant is capable of flowing; an electrode configured to output energy to ablate nerve tissue in an airway wall of an airway of a bronchial tree; and an expandable balloon having a collapsed state and an expanded state, wherein the expandable balloon in the expanded state is dimensioned to contact the airway wall of the bronchial tree, wherein the expandable balloon is coupled to the elongated body and configured to receive and contain the coolant such that the coolant cools the electrode and expandable balloon when the catheter is in contact with the airway wall to limit or prevent damage to tissue between the electrode and the nerve tissue, wherein the electrode is coupled to the expandable balloon such that the electrode is moved towards the airway wall as the expandable balloon moves from the collapsed state to the expanded state, wherein, when the expandable balloon is in the expanded state, portions of the expandable balloon are configured to contact an inner surface of the airway wall immediately adjacent to and on both proximal and distal sides of the electrode, wherein an axial dimension of the electrode is less than an axial dimension of each of the portions of the expandable balloon in contact with the inner surface of the airway wall, the axial dimension of the electrode and the axial dimension of each of the portions extending along a longitudinal axis of the airway; wherein the treatment controller is configured to control power to the electrode when coolant is circulated within the expandable balloon to output a sufficient amount of energy to damage the nerve tissue at a first location along the airway spaced radially outwardly from the inner surface of the airway wall at an electrode-tissue interface so as to attenuate transmission of signals to and/or from mucous producing cells at a second location along the airway so as to reduce a production of mucous from the mucous producing cells, while limiting damage to at least a portion of the tissue between the first location and the electrode-tissue interface and immediately adjacent the electrode-tissue interface.
 2. The catheter of claim 1, wherein the electrode extends circumferentially about the expandable balloon when the expandable balloon is in the expanded state.
 3. The catheter of claim 1, wherein the electrode is positioned outside of the expandable balloon such that the electrode is capable of outputting energy directly to the airway wall.
 4. The catheter of claim 1, wherein the electrode is embedded in a wall of the expandable balloon.
 5. The catheter of claim 1, wherein the electrode is coupled to an exterior surface of the expandable balloon or an interior surface of the expandable balloon.
 6. The catheter of claim 1, further comprising a plurality of circumferentially spaced apart electrodes coupled to the expandable balloon and configured to output energy.
 7. The catheter of claim 1, further comprising an ultrasound probe capable of outputting ultrasound energy through a wall of the expandable balloon for imaging.
 8. The catheter of claim 1, wherein the electrode and the expandable balloon are configured to raise a temperature of the nerve tissue to cause cell death of the nerve tissue while maintaining a temperature of the tissue between the first location and the electrode-tissue interface and immediately adjacent the electrode-tissue interface below a temperature at which cell death occurs.
 9. The catheter of claim 1, wherein the electrode and the expandable balloon are configured to cooperate to raise the temperature of tissue at a depth of 2 mm to 8 mm in the airway wall to cause cell death, while maintaining tissues at a depth less than 2 mm in the airway wall at a temperature below a temperature at which cell death occurs.
 10. The system of claim 1, further comprising: a coolant source coupled to the catheter, and a radiofrequency generator coupled to the catheter and the controller; wherein the coolant source is configured to deliver coolant to the expandable balloon and the radiofrequency generator is configured to deliver energy to the electrode to concentrate heating in outer layers of the airway wall.
 11. The system of claim 10, wherein the coolant source is configured to output a low temperature coolant that absorbs thermal energy to cool tissue contacting the expandable balloon.
 12. The system of claim 10, further comprising: a bronchoscope having a delivery lumen for receiving the catheter.
 13. A method of treating an airway condition caused by excessive intraluminal mucus, mucous glands hypertrophy, or both, the method comprising: using the system of claim 1, causing damage to nerve tissue at a first location along the airway so as to attenuate transmission of signals to and/or from mucous producing cells at a second location along the airway so as to reduce a production of mucous from the mucous producing cells.
 14. The method of claim 13, wherein causing damage to nerve tissue comprises damaging efferent nerve tissue to inhibit signals from being transmitted from the brain to mucous producing cells of the airway.
 15. The method of claim 13, wherein causing damage to nerve tissue disrupts a baseline level of mucous secretion.
 16. The method of claim 13, wherein causing damage to nerve tissue attenuates transmission of signals traveling along vagus nerves that cause mucus production.
 17. The method of claim 16, wherein attenuation of the transmission of signals comprises decreasing signal amplitude or weakening transmission of signals.
 18. The method of claim 13, wherein attenuation of the transmission of signals comprises hindering, limiting, blocking, and/or interrupting transmission of signals.
 19. The method of claim 13, wherein the method decreases a sufficient amount of mucus production to cause substantial decrease in coughing and/or airflow resistance.
 20. The method of claim 13, wherein the method further comprises, after causing damage to nerve tissue: providing a questionnaire or test to assess a subject's response to treatment by assessing a subject's quality of life and comparing the assessment to an assessment of the subject's quality of life before damaging the nerve tissue.
 21. The method of claim 13, wherein causing damage to nerve tissue comprises: outputting energy from the electrode of the catheter positioned in the airway to heat and ablate the nerve tissue along the airway wall at the first location; and cooling a portion of the expandable balloon to cool an inner portion of the airway wall while outputting the energy to inhibit damage to the inner portion of the wall while the nerve tissue is ablated.
 22. The method of claim 13, wherein causing damage to nerve tissue comprises: delivering energy from the electrode of the catheter positioned in the airway to destroy the nerve tissue along the wall of the airway while avoiding injury to airway tissue distal the damaged nerve tissue.
 23. The method of claim 13, wherein the nerve tissue is positioned between a trachea and a lung of a subject.
 24. The method of claim 13, wherein causing damage to nerve tissue includes ablating nerve tissue of a nerve trunk along a right main bronchus, a left main bronchus, or both. 